Powered devices operable for producing a pulsatile stream of liquid for use in oral irrigation have long been known and are currently available commercially. Many such devices incorporate a refillable tank for receiving the treatment liquid--typically water--and require an electric current for developing a pulsating pressure used to deliver a water stream to an outlet tip or the like. Because spillage and dripping of the delivered liquid are common during their operation, these oral irrigators are most commonly used in the bathroom, proximate sinks and bathtubs and other supplies of running water, raising the distinct possibility of serious injury through shock or electrocution should the electrically-operated device inadvertently become submersed in water or develop an electrical short circuit.
Other such devices seek to overcome this drawback by providing non-electrical operating power. For example, U.S. Pat. No. 4,564,005 to Marchand et al. discloses an oral irrigating device designed for use in a bathtub or shower stall and operated solely by the incoming stream of continuous flow (i.e. nonpulsatile) water. The Marchand device includes a housing connected between the water supply pipe and the shower head, wherein the water stream is split into one branch that continues on to the shower head and a second branch that powers a turbine disposed in the housing. This second branch is again split into a first channel that is directed into turbine rotating contact with the turbine periphery and a second channel which is fed into interruptive communication with an off-axis aperture in the turbine disk to generate a pulsatile flow of the water from the continuous flow stream. The pulsatile flow is then directed, through an elongated conduit, to a hand-held tip for user-controlled direction of the pulsating output flow onto the teeth and gums. The hand-held tip also includes an optional open-mesh cage therewith for holding a tablet-form dentifrice or cleanser or other additive which, as the pulsating stream flows through the tip, melts and thereby mixes with the pulsatile stream for discharge from the tip.
Although the Marchand device is advantageously powered solely from the incoming continuous flow water stream, it suffers from several drawbacks that reduce its commercial desireability. For example, the operating components, such as the turbine, of the unit are contained in an elongated housing that is mounted physically between the water supply pipe and the shower head. The fact that this housing incorporates these components significantly increases its size and thereby substantially displaces the shower head from its originally-intended position over the bathtub or within the shower stall, a change which not all such installations are capable of practically or conveniently accommodating. In addition, undiscovered crimping or other blockage of the conduit connecting the housing to the hand-held discharge tip could quickly damage the unit's internal operating components located in the housing, such as the turbine, during operation or attempted operation of the device. Furthermore, in the event that it does become necessary to effect repairs to the turbine or other operating elements of the Marchand device, both the housing and the attached shower head must be removed from and then replaced on the water supply pipe since all of the unit's operating components are located in the housing. These procedures are extremely time consuming, potentially expensive should a professional plumber be required, and could easily result in leaks due to improperly-prepared or sealed connections when the various plumbing elements are rejoined both while the unit is being repaired and, again, when it must be reinstalled.
Another drawback lies in the manner in which the Marchand device provides for the mixing of an additive with the pulsatile water stream to be discharged from the hand-held tip. Such mixing occurs when the pulsatile stream causes melting of the solid-form additive and, as should be apparent, will result in inconsistent and virtually unpredicatable concentrations or ratios of additive to water. As a consequence, the effectiveness of the additive on the user's teeth and/or gums will be sharply reduced or, in some situations, almost entirely eliminated.